Method and device for comprehensive characterization and monitoring of exhaust gas and control of engines, and components for aftertreatment of exhaust gases

ABSTRACT

Device of modular construction which permits the simultaneous or not-simultaneous recording and characterization of solid and liquid particles and gaseous components of engine exhaust gases on various test supports, with only small or no modification of the test support. Methods are based on individual or combined usage of laser scattering techniques, laser-induced breakdown spectroscopy, laser-induced ionization spectroscopy, laser-induced atomic fluorescence spectroscopy, IR-/VIS-/UV-laser absorption spectroscopy and laser-induced incandescence. Use of individual or combined usage of such devices permits the analysis of raw exhaust gas, the conditioned and/or treated exhaust gases for monitoring and checking working pattern of engine, individual components of exhaust gas treatment and/or total system on test beds and on vehicle and can be used for control of motor and/or exhaust components, such as catalysts and particle filters, on test beds and in driven usage, e.g., in connection with, or as part of, on-board diagnostic system.

CROSS-REFERENCE TO RELATED APPLICATIONS

The instant application is a continuation of U.S. patent applicationSer. No. 10/477,200 filed on Nov. 17, 2003 , which issued as U.S. Pat.No. 7,084,963 on Aug. 1, 2006 and which is a U.S. National StageApplication of International Application No. PCT/EP02/05042,filed May 8,2002, and which claims priority under 35 U.S.C. § 119 of German PatentApplication No. 101 24 235.2 filed on May 18, 2001. The disclosure ofU.S. Application No. 10/477,200 is hereby expressly incorporated byreference herein in its entirety.

BACKGROUND OF THE INVENTION

1. Field of the Invention

To comply with future regulations on exhaust gases, measuring,monitoring and regulating systems will be required which can record thepreset exhaust gas values and monitor compliance with them as well as,if possible, regulate the combustion system and/or frequently downstreampositioned components of the exhaust gas after treatment, e.g.,catalytic converter systems or filter systems, with these measured orcontrol values towards the desired emissions or provide thecorresponding regulating variables in the control system. Such systemsthat, if possible, comprehensively characterize the exhaust gas, i.e.,that record all the gaseous, liquid and solid constituents as far aspossible at the same time, will be increasingly used in future in theresearch laboratories and test beds of the auto industry and itssuppliers, in the service centers (e.g., comparable with today's Boschtest centers) and, at least in partial areas, also in the motor vehicleitself, e.g., as part of an on-board diagnostics (OBD) system. Inaddition to the monitoring, improvement and regulation of the internalcombustion engine via measurements in the raw exhaust gas, these systemscan likewise also be used for stand-alone or integrated components forexhaust gas after treatment through measurements before and/or after therespective components, e.g., the catalytic converters for treatinggaseous and/or particulate exhaust gas constituents or the correspondingfilter systems, thus, e.g., also for monitoring and regulating theregeneration process of particle filters.

SUMMARY OF THE INVENTION

The subject matter of the invention is the individual, specific—but inparticular also the joint—use of different optical, mostly laser-based,laser diode-based or diode laser-based measuring processes forcharacterizing exhaust gas and individual components important forcharacterizing exhaust gas and the combination of devices that combinethese measuring processes in a targeted manner. Some of the methods arealready known or have already been tested for the individual task, buthave not been used simultaneously with other methods in thiscombination. Other methods have not yet been used even individually inthe field of application targeted here and thus also represent anindependent invention in their individual use.

Engine exhaust gases comprise gaseous constituents (e.g., oxygen,unburned fuel constituents such as hydrocarbons or hydrogen itself,carbon monoxide and carbon dioxide, nitrogen monoxide, nitrogen dioxideand N₂O, sulfur compounds, etc.) and particulates that can be present inliquid form (e.g., as condensates, such as water, sulfuric acid, etc.,or aqueous solutions, e.g., urea-water solutions in connection withcatalytic converter systems) or in solid form (e.g., soot particles,metal compounds, ash, etc.) often also with organic deposits or, e.g.,also deposits of sulfur compounds thereon. In this invention differentmeasuring methods and processes are listed and used in part incombination and simultaneously for recording and characterizing thesedifferent constituents.

Solid particles of the exhaust gas include soot particles (pure carbon)that with the aid of the laser-induced incandescence process (alsocalled laser-induced incandescence (LII)) can be comprehensively (GermanPatent DE 19606005) and simultaneously (German Patent Application DE19904691 A1) characterized with regard to its volume or massconcentration, its primary particle size, its aggregate size and valuesthat can be derived there from. This process is used here according tothe invention for the first time in combination with individual orseveral other measuring processes referenced in this invention. Thelaser (or diode laser) used here to excite the thermal particleradiation or the laser diode used to this end is also usedsimultaneously or one after the other as an excitation light source forindividual or several of the other measuring processes. Alternatively,one or more other excitation beam sources can be used parallel theretowith the same beam course in the measurement volume or spatiallydisplaced thereto in one or more other beam courses in the measurementvolume. The detection of the LII signal can take place offset in time tothe measurement signals of individual or of all other processes with inpart the same detection beam course in that conditional on the processfor the other measuring processes in partial branches of theregistration beam course other optical components can be combined or cantake place simultaneously using different detection beam courses,whereby all of these detection beam courses or individual beam coursescan be executed in the backscattering direction relative to the inputbeam direction; however they can also have any other direction arrangedat an angle to the input beam direction, whereby conditional on thesystem an arrangement at 90 degrees or 180 degrees is advantageous insome processes. Records of the measurement signals of the differentprocesses in selected, in part also different, spectral regions takesplace via wavelength-selective optical components, e.g., filters,spectrometers, monochromators, etc., with photomultipliers, photodiodes,streak cameras, CCD cameras or similar optoelectronic components thatcan produce electrical signals from optical measurement signals. Theseelectrical signals can be further processed for imaging the measurementsignals, for data processing and/or also used directly for regulatingpurposes. Three possible arrangements for three different measuringprocesses for a mainly backscattering arrangement (FIG. 1), a 90-degreearrangement (FIG. 2) and a 180-degree arrangement (FIG. 3) are showndiagrammatically according to the device by way of example in FIGS. 1through 3. The pipe segments described in patent application DE 19904691A1 can be used advantageously in particular for measurements in exhaustgas, which pipe segments there integrate all the features essential forthe LII sensor and in this invention at the same time also integrate theessential features of the other processes.

The other measuring processes to be used respectively alone or also incombination with the LII technique or with one another at the same timeor one after the other characterize other components of the engineexhaust gas.

Solid constituents of the exhaust gas are furthermore particles ofdifferent metals, partially in almost pure form, as metal oxides or asmetal compounds of another kind, silicon compounds and ash. Acharacterization, e.g., identification and concentration of theindividual constituents, is possible, e.g., via laser-induced ionizationspectroscopy (LIS)—often called laser-induced breakdown spectroscopy(LIBS) in specialized scientific literature in a special embodimentusing highly tempered plasmas and also thus termed below in this patentspecification—in which via the laser action, parts of the particles orthe particle as a whole is vaporized and partially ionized. Specificallythis occurs with LIBS in that during the irradiation of an extremelyhigh power density of over a hundred MW/cm² a high-temperaturemicroplasma of high electron density is produced with temperatures ofseveral thousand degrees, at which every material is decomposed,evaporated and ionized. The subsequent radiation is at first wide-band(from the x-ray region to infrared), after a brief time lag—with cooleddown plasma with neutral atoms in excited states—species-selectiveregarding the atoms present (e.g., for Al, Ba, Ca, Co, Cr, Cu, Eu, Fe,Hg, Mg, Mn, Mo, Na, Ni, Pb, Sb, Si, Sr, Ti, V, W and Zn in A. Ciucci etal., Appl. Phys. B 63 (1996) 185-190) and can be assigned to differentatomic constituents, e.g., via comparisons with spectra known from theliterature and/or via calibrated measurements or laboratorymeasurements. In this manner ashes or such deposits (D. K. Ottesen,Proc. 24^(th) Combustion Symposium, 1992, p. 1579-1585) or deposits onthe solid particles can also be identified and measured. Laser-inducedbreakdown spectroscopy (LIBS) is used here according to the inventionfor the first time to test the exhaust gas of engine combustionprocesses or the exhaust gas treated by way of catalytic converters orfilters, which can be implemented alone or also in combination withother processes. This technique thus represents by way of example insimultaneous use with LII one of the processes in FIGS. 1 through 3.

The soot particles as solid particles can likewise be detected andmeasured by way of the LIBS technique, either simultaneously with othersolid particles or alone. This technique can likewise be used forcharacterizing liquid particles and gaseous constituents.

If the solid, liquid or gaseous constituents to be detected are presentin amounts that are below the LIBS detection limit (approx. 100 ppb), asan alternative to LIBS, laser atomic fluorescence spectroscopy (LAFS) isused, for example, which is thus accordingly used according to theinvention for such low detection limits in engine exhaust gases.

Liquid constituents of the raw exhaust gas behind the engine and/or ofthe treated exhaust gas after components of the exhaust gas aftertreatment can comprise, e.g., water, sulfuric acid, nitric acid orurea-water solutions or can be contained therein. To test andcharacterize such exhaust gas constituents according to the inventionhere for the first time the laser Raman scattering (LRS) technique isused in linear (spontaneous) or also in non-linear form, alone or incombination with LII and/or one or more of the other processes. It isexcited via lasers (also diode lasers) or laser diodes, to which end anexcitation light source specifically for this process or the excitationlight source of the LII technology or that of another process can beused, whereby in a process-specific favorable manner the shortestpossible excitation wavelengths are selected that can also be realized,e.g., through a frequency multiplication of the output radiation of alaser likewise used for another process. The Raman scattered lightspectrally shifted due to the light-molecule interaction in amolecule-specific manner according to the Raman shift (G. Herzberg,Molecular Spectra and Molecular Structure, vol. I through III, KriegerPubl. Company, Malabar, Fla., 1989 or 1991; vol. IV with G. Huber, VanNostrand, Princeton-N.Y., 1979; P. W. B. Pearse and A. G. Gaydon, TheIdentification of Molecular Spectra, Chapman and Hall, London 1976; B.Schrader, ed., Infrared and Raman Spectroscopy, VCH Verlagsgesellschaft,Weinheim 1995) after spectral selection by way of, e.g., interferencefilters or spectrometers or monochromators is conveyed to detectors ofthe above-mentioned type, whereby it has a favorable effect that therelatively small scattering cross section for gases is considerablylarger for liquids (A. Weber (ed.), Raman Spectroscopy of Gases andLiquids, Springer-Verlag, Berlin 1979, and therein specifically H. W.Schrötter and H. W. Klöckner, Raman scattering cross sections in gasesand liquids, p. 123-166) and this technique can thus be used accordingto the invention. This can take place individually or in combinationwith other techniques with, e.g., one of the devices showndiagrammatically in FIGS. 1 through 3, in particular favorably in aright-angled arrangement (FIG. 2) between input beam direction anddetection direction. Evaluating the spectra and obtaining results takesplace in fundamentally the same ways as is given for gas phase Ramanspectroscopy and described, e.g., in A. Leipertz, Dissertation, RuhrUniversity Bochum, 1979; A. Leipertz, Habilitationsschrift, RuhrUniversität Bochum 1984 (p. 380-382 regarding a concentrationmeasurement), in invention DE 19827533 for determining the vapor phasecomposition in evaporating injection sprays or in patent application DE19702006 A1 for determining calorific value by way of Raman scattering.Water can thus be measured with relatively wide vibration bands, e.g.,with Raman shifts of approx. 675, approx 1640 and approx. 3400 wavenumbers, sulfuric acid, i.a., via the SO₄ ^(2—)vibration at approx. 980wave numbers and nitric acid, e.g., at 1045 wave numbers. For theseconstituents and others of interest there is a plurality of other Ramanshifts that can be used likewise and/or alternatively, which increase innumber with increasing complexity of the molecule according to theincreasing number of possible vibration states and which can be takenfrom many publications on Raman spectroscopy and, e.g., from theabove-mentioned books and publications.

Since material in solid aggregate form, and thus also the solidparticles of engine exhaust gas, is also Ramon-active, alternatively toLIBS, LRS—or non-linear forms of Raman scattering—are also usedaccording to the invention to investigate the solid particles.

For the gaseous exhaust gas constituents NO_(x), NO, NO₂, N₂O, CO, HClimited by international agreements or draft agreements as well as,e.g., H₂O and NH₃, there are measuring systems commercially available(e.g., on the basis of the chemical luminescence technique, infraredabsorption spectroscopy, preferably in the near infrared region, e.g.,also as Fourier Transform Infrared (FTIR) analyzers, as flame ionizationdetectors, etc.). However, so far none of them have been used directlyin the exhaust gas pipe—so in principle only via specimen-takingprocedures—or in combination with particle detection systems, as is hereintroduced for the first time according to the invention. In addition tothe liquid phase, according to the invention here the same constituentsin gas or vapor form are also recorded and measured via the Ramanscattering with the same or different Raman shift (water, e.g., with aRaman shift of approx. 1595 or approx. 3652 wave) numbers oradditionally also e.g., NH₃ (e.g., with a Raman shift of approx. 3334wave numbers), SO₂ (e.g., with a Raman shift of approx. 519 and approx.1151 wave numbers), etc., and in particular the components occurringwith high concentrations. Alternatively, or also additionally in thisinvention the determination and measurement of these gaseousconstituents are carried out advantageously with variable lasers, laserdiodes or diode lasers which via absorption spectroscopy in theinfrared, visible and/or ultraviolet spectral region make it possible totest several constituents with only one absorption light source, or withdifferent absorption light sources (laser (diode) absorptiontechnique—LAT) selected for the respective constituents. In addition,oxygen is also measured, in order to thus conduct, e.g., an enginecontrol according to today's 8 probes with a 8 probe working across theentire concentration range, e.g., according to invention DE 19541516.Independent of a device according to FIGS. 1-3, or also in combinationwith one like this, a transmitted light arrangement for stretching thenecessary absorption lengths is used in the absorption techniques,whereby to extend the absorption length a multi-pass arrangement e.g.,made of reflecting mirrors, is selected sweeping over the measurementvolume, or also one such outside the exhaust gas main stream (e.g., in abypass arrangement) where alternatively simple measurement cells ofcorresponding length are also used.

The invention also provides for a process for determining properties ofliquid particles of engine exhaust gas, wherein the process comprisesdetecting Raman scattering produced in a test area by excitation withone of a laser, a laser diode, and a diode laser and determining atleast one of a type and composition of individual constituents of theliquid particles of the engine exhaust gas and concentrations ofindividual constituents of the liquid particles of the engine exhaustgas.

The determining may comprise determining concentrations of theindividual constituents of the liquid particles of the engine exhaustgas, and wherein the concentrations of individual constituents of theliquid particles of the engine exhaust gas comprise at least one of anumber concentration, a mass concentration, and a volume concentration.

The determining may comprise determining concentrations, via partialdensities, of the individual constituents of the liquid particles of theengine exhaust gas, and wherein the concentrations of individualconstituents of the liquid particles of the engine exhaust gas compriseat least one of a number concentration, a mass concentration, and avolume concentration.

The engine exhaust gas may be in a raw state. The engine exhaust gas maybe at least one of conditioned exhaust gas and diluted exhaust gas. Theengine exhaust gas may comprise one of water, sulfuric acid, nitricacid, water in pure form, sulfuric acid in pure form, nitric acid inpure form. The engine exhaust gas may comprise at least one of otherconstituents and aqueous solutions. The engine exhaust gas may comprisean urea water solution. The engine exhaust gas may comprise a mixture ofone of water, sulfuric acid, nitric acid, and water in pure form,sulfuric acid in pure form, nitric acid in pure form. The process maydetermine properties of liquid particles of engine exhaust gas behindcomponents of exhaust gas after treatment.

The invention also provides for a process for determining properties ofsolid particles of engine exhaust gas, wherein the process comprisesdetecting Raman scattering produced in a test area by excitation withone of a laser, a laser diode, and a diode laser and determining atleast one of a type and composition of individual constituents of thesolid particles of the engine exhaust gas and concentrations ofindividual constituents of the solid particles of the engine exhaustgas.

The determining may comprise determining concentrations of individualconstituents of the solid particles of the engine exhaust gas, andwherein the concentrations of individual constituents of the solidparticles of the engine exhaust gas comprise at least one of a numberconcentration, a mass concentration, and a volume concentration.

The determining may comprise determining concentrations of individualconstituents of the solid particles of the engine exhaust gas, andwherein the concentrations of individual constituents of the solidparticles of the engine exhaust gas comprise at least one of a numberconcentration, a mass concentration, and a volume concentration.

The engine exhaust gas may be in a raw state. The engine exhaust gas maybe at least one of conditioned exhaust gas and diluted exhaust gas. Thesolid particles may comprise one of soot particles, metals, metaloxides, metal compounds, silicon compounds, and ash. The process maydetermine properties of solid particles of engine exhaust gas behindcomponents of exhaust gas after treatment.

The invention also provides for a process for determining aconcentration of gaseous constituents of engine exhaust gas, wherein theprocess comprises detecting Raman scattering produced in a test area byexcitation with one of a laser, a laser diode, and a diode laser anddetermining a type and concentration of individual gaseous constituentsof the engine exhaust gas.

The determining may comprise determining a type and concentration, viapartial densities, of individual gaseous constituents of the engineexhaust gas. The concentration of individual gaseous constituents ofengine exhaust gas may comprise one of a number concentration ofindividual gaseous constituents of engine exhaust gas, a massconcentration of individual gaseous constituents of engine exhaust gas,and a volume concentration of individual gaseous constituents of engineexhaust gas.

The engine exhaust gas may be in a raw state. The engine exhaust gas maybe at least one of conditioned exhaust gas and diluted exhaust gas. Theindividual gaseous constituents may comprise NO_(x), NO, NO₂, N₂O, CO,HC, O₂, H₂O, and NH₃. The process may determine a concentration ofgaseous constituents of engine exhaust gas behind components of exhaustgas after treatment.

The invention also provides for a process for determining properties ofsolid particles of engine exhaust gas, wherein the process comprisesdetecting radiation produced in a test area by laser-induced breakdownspectroscopy (LIBS) after irradiation with one of a laser, a laserdiode, and a diode laser and determining a type and composition of thesolid particles of the engine exhaust gas.

The engine exhaust gas may be in a raw state. The engine exhaust gas maybe at least one of conditioned exhaust gas and diluted exhaust gas. Thesolid particles may comprise one of soot particles, metals, metaloxides, metal compounds, silicon compounds, and ash. The process maydetermine properties of solid particles of engine exhaust gas behindcomponents of exhaust gas after treatment.

The invention also provides for a process for determining properties ofsolid particles of engine exhaust gas, wherein the process comprisesdetecting radiation produced in a test area after irradiation with oneof a laser, a laser diode, and a diode laser, and after vaporization andionization of one of the solid particles and parts of the solidparticles and determining a type and composition of the solid particlesof the engine exhaust gas.

The engine exhaust gas may be in a raw state. The engine exhaust gas maybe at least one of conditioned exhaust gas and diluted exhaust gas. Thesolid particles may comprise one of soot particles, metals, metaloxides, metal compounds, silicon compounds, and ash. The process maydetermine properties of solid particles of engine exhaust gas behindcomponents of exhaust gas after treatment.

The invention also provides for a process for determining properties ofliquid particles of engine exhaust gas, wherein the process comprisesdetecting radiation produced in a test area after irradiation with oneof a laser, a laser diode, and a diode laser, and after vaporization andionization of one of the liquid particles and parts of the liquidparticles and determining a type and composition of the liquid particlesof the engine exhaust gas.

The engine exhaust gas may be in a raw state. The engine exhaust gas maybe at least one of conditioned exhaust gas and diluted exhaust gas. Theengine exhaust gas may comprise one of water, sulfuric acid, nitricacid, water in pure form, sulfuric acid in pure form, nitric acid inpure form. The engine exhaust gas may comprise at least one of otherconstituents and aqueous solutions. The engine exhaust gas may comprisean urea water solution. The engine exhaust gas may comprise a mixture ofone of water, sulfuric acid, nitric acid, and water in pure form,sulfuric acid in pure form, nitric acid in pure form. The process maydetermine properties of liquid particles of engine exhaust gas behindcomponents of exhaust gas after treatment.

The invention also provides for a process for determining properties ofliquid particles of engine exhaust gas, wherein the process comprisesdetecting radiation produced in a test area by laser-induced breakdownspectroscopy (LIBS) after irradiation with one of a laser, a laserdiode, and a diode laser and determining a type and composition of theliquid particles of the engine exhaust gas.

The engine exhaust gas may be in a raw state. The engine exhaust gas maybe at least one of conditioned exhaust gas and diluted exhaust gas. Theengine exhaust gas may comprise one of water, sulfuric acid, nitricacid, water in pure form, sulfuric acid in pure form, nitric acid inpure form. The engine exhaust gas may comprise at least one of otherconstituents and aqueous solutions. The engine exhaust gas may comprisean urea water solution. The engine exhaust gas may comprise a mixture ofone of water, sulfuric acid, nitric acid, and water in pure form,sulfuric acid in pure form, nitric acid in pure form. The process maydetermine properties of liquid particles of engine exhaust gas behindcomponents of exhaust gas after treatment.

The invention also provides for a process for determining concentrationsof gaseous constituents of engine exhaust gas, wherein the processcomprises detecting radiation produced in a test area by laser-inducedbreakdown spectroscopy (LIBS) after irradiation with one of a laser, alaser diode, and a diode laser and determining a type and concentrationof individual gaseous constituents of the engine exhaust gas.

The concentration of individual gaseous constituents of engine exhaustgas may comprise one of a number concentration of individual gaseousconstituents of engine exhaust gas, a mass concentration of individualgaseous constituents of engine exhaust gas, and a volume concentrationof individual gaseous constituents of engine exhaust gas.

The engine exhaust gas may be in a raw state. The engine exhaust gas maybe at least one of conditioned exhaust gas and diluted exhaust gas. Theindividual gaseous constituents may comprise NO_(X), NO, NO₂, N₂O, CO,HC, O₂, H₂O, and NH₃. The process may determine concentrations ofgaseous constituents of engine exhaust gas behind components of exhaustgas after treatment.

The invention also provides for a process for determining properties ofat least one of liquid particles and solid particles of engine exhaustgas, wherein the process comprises detecting an atomic fluorescenceemission produced in a test area by excitation with one of a laser, alaser diode, and a diode laser and determining a type and composition ofthe liquid and/or solid particles of the engine exhaust gas andconcentrations of individual constituents.

The engine exhaust gas may be in a raw state. The engine exhaust gas maybe at least one of conditioned exhaust gas and diluted exhaust gas.

The process may further comprise determining concentrations ofindividual constituents, which concentrations comprise at least one of anumber concentration, a mass concentration and a volume concentration.

The process may further comprise calculating concentrations ofindividual constituents using at least one of a measuring signal and anatomic fluorescence measuring signal.

The process may further comprise, after ionization, calculatingconcentrations of individual constituents using at least one of ameasuring signal and an atomic fluorescence measuring signal.

The engine exhaust gas may comprise one of water, sulfuric acid, nitricacid, water in pure form, sulfuric acid in pure form, nitric acid inpure form. The engine exhaust gas may comprise at least one of otherconstituents and aqueous solutions. The engine exhaust gas may comprisean urea water solution. The engine exhaust gas may comprise a mixture ofone of water, sulfuric acid, nitric acid, and water in pure form,sulfuric acid in pure form, nitric acid in pure form. The solidparticles may comprise one of soot particles, metals, metal oxides,metal compounds, silicon compounds, and ash. The process may determineproperties of at least one of liquid particles and solid particles ofengine exhaust gas behind components of exhaust gas after treatment.

The invention also provides for a process for determining concentrationsof gaseous constituents of engine exhaust gas, wherein the processcomprises detecting parts of laser radiation absorbed after irradiationin a test area with one of a variable laser, a variable laser diode, anda variable diode laser and determining a type and concentration ofindividual gaseous constituents of the engine exhaust gas.

The detecting may comprise detecting parts of laser radiation, in atleast one of an infrared spectral region, a visible spectral region, andan ultraviolet spectral region, absorbed after irradiation in a testarea with one of a variable laser, a variable laser diode, and avariable diode laser.

The engine exhaust gas may be in a raw state. The engine exhaust gas maybe at least one of conditioned exhaust gas and diluted exhaust gas. Theconcentration of individual gaseous constituents may comprise at leastone of a number concentration, a mass concentration and a volumeconcentration. The engine exhaust gas may comprise one of water,sulfuric acid, nitric acid, water in pure form, sulfuric acid in pureform, nitric acid in pure form. The engine exhaust gas may comprise atleast one of other constituents and aqueous solutions. The engineexhaust gas may comprise an urea water solution. The engine exhaust gasmay comprise a mixture of one of water, sulfuric acid, nitric acid, andwater in pure form, sulfuric acid in pure form, nitric acid in pureform. The individual gaseous constituents may comprise NO_(X), NO, NO₂,N₂O, CO, HC, O₂, H₂O, and NH₃. The process may determine concentrationsof gaseous constituents of engine exhaust gas behind components ofexhaust gas after treatment.

The invention also provides for a device for practicing any of theprocesses described above wherein device comprises a detector unit and aplurality of optical components.

The invention also provides for a device for practicing any of theprocesses described above wherein device comprises a detector unitcomprising one of optical fibers and parts of optical fibers.

The invention also provides for a device for practicing any of theprocesses described above wherein device comprises a device enclosingthe engine exhaust gas and a device for one of avoiding contaminationand reducing contamination.

The invention also provides for a system for determining concentrationsof gaseous constituents of engine exhaust gas, wherein the systemcomprises a test area comprising an optical access, a light sourceemitting an optical beam towards the optical access, the light sourcecomprising one of a laser, a laser diode, and a diode laser, an opticaldevice disposed between the optical access and the light source, atleast one detector unit receiving an optical beam passing through theoptical device from the optical access, and an electronic processingsystem communicating with the at least one detector unit.

The invention also provides for a system for determining concentrationsof gaseous constituents of engine exhaust gas, wherein the systemcomprises a test area comprising a first optical access and a secondoptical access, a light source emitting an optical beam towards thefirst optical access, the light source comprising one of a laser, alaser diode, and a diode laser, an optical device disposed between thefirst optical access and the light source, at least one detector unitreceiving an optical beam from the second optical access, and anelectronic processing system communicating with the at least onedetector unit.

The invention also provides for a process for determining properties ofsolid particles of engine exhaust gas, wherein the process comprisesdetecting radiation produced in a test area by laser-induced breakdownspectroscopy (LIBS) after irradiation with one of a laser, a laserdiode, and a diode laser, detecting radiation produced in the test areaby laser-induced incandescence (LII) after irradiation with one of alaser, a laser diode, and a diode laser, and determining a type andcomposition of the solid particles of the engine exhaust gas.

The invention also provides for a process for determining properties ofliquid particles of engine exhaust gas, wherein the process comprisesdetecting radiation produced in a test area by laser-induced breakdownspectroscopy (LIBS) after irradiation with one of a laser, a laserdiode, and a diode laser, detecting radiation produced in the test areaby laser-induced incandescence (LII) after irradiation with one of alaser, a laser diode, and a diode laser, and determining a type andcomposition of the liquid particles of the engine exhaust gas.

The invention also provides for a process for determining concentrationsof gaseous constituents of engine exhaust gas, wherein the processcomprises detecting radiation produced in a test area by laser-inducedbreakdown spectroscopy (LIBS) after irradiation with one of a laser, alaser diode, and a diode laser, detecting radiation produced in the testarea by laser-induced incandescence (LII) after irradiation with one ofa laser, a laser diode, and a diode laser, and determining a type andconcentration of individual gaseous constituents of the engine exhaustgas.

The invention also provides for a process for determining properties ofliquid particles of engine exhaust gas, wherein the process comprisesdetecting Raman scattering produced in a test area by excitation withone of a laser, a laser diode, and a diode laser, detecting radiationproduced in the test area by laser-induced incandescence (LII) afterirradiation with one of a laser, a laser diode, and a diode laser, anddetermining at least one of a type and composition of individualconstituents of the liquid particles of the engine exhaust gas, andconcentrations of individual constituents of the liquid particles of theengine exhaust gas.

The invention also provides for a process for determining properties ofsolid particles of engine exhaust gas, wherein the process comprisesdetecting Raman scattering produced in a test area by excitation withone of a laser, a laser diode, and a diode laser, detecting radiationproduced in the test area by laser-induced incandescence (LII) afterirradiation with one of a laser, a laser diode, and a diode laser, anddetermining at least one of a type and composition of individualconstituents of the solid particles of the engine exhaust gas, andconcentrations of individual constituents of the solid particles of theengine exhaust gas.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1-4 show by way of example possible embodiments of devicesdesigned according to the invention, wherein:

FIG. 1 shows a device in which a detection side is constructed on thesame side of the test area on which the input beam side is also located(backscatter arrangement);

FIG. 2 shows a device according to the invention in which by way ofexample input beam and recording beam form a 90 degree arrangement forthree different techniques;

FIG. 3 shows a device according to the invention in diagrammatic form inwhich the signal beam course is constructed behind the test volume, thusopposite the input beam side (thus as a 180-degree or transmissionarrangement); and

FIG. 4 shows in diagrammatic form a possible application of theinvention in the testing and characterization of an engine exhaust gas.

DETAILED DESCRIPTION OF THE INVENTION

Possible embodiments of devices designed according to the invention areshown by way of example in FIGS. 1 through 3, in which only thosedevices are represented in which several of the above-mentionedprocesses are used in combination simultaneously or one after the other.Advantageously, in the devices optical components of the input beamcourse and detection beam course provided with measures for avoiding orminimizing contamination (e.g., air-rinsed, heated, etc.) are includedin a device comprising the test volume (e.g., ring or channel segment),e.g., according to patent application DE 19904691 A1, through which theraw exhaust gas and/or pretreated or after treated exhaust gas can flowwithout special dilution and unconditioned (e.g., cooled or heated) andcan thereby be characterized according to the invention. Alternatively,devices can also be constructed in which according to the invention onlythe linear Raman scattering (LRS) is used to characterize the liquidand/or solid particles and/or gaseous constituents of the exhaust gasand/or only laser-induced breakdown spectroscopy (LIBS) is used for thesolid particles and/or only the laser (diode) absorption technique (LAT)using variable radiation sources is used to record the gaseous exhaustgas constituents, alone or in combination with one another or inparticular with the LII technique for recording the soot particlevalues.

FIG. 1 shows a device of this type in which the detection side isconstructed on the same side of the test area on which the input beamside is also located (backscatter arrangement). Such an arrangement hasthe advantage that it requires only one optical access to the test area.A laser, a diode laser or a laser diode that radiates its excitationlight beam into the test volume via an optical beam course 2 through anoptical access 4, which is advantageously provided with a device (e.g.,heating or air rinsing) for avoiding or reducing contamination, servesas the excitation light source 1, which test volume is located inside apipe or channel segment 5 that can be directly installed in the exhaustgas pipe and thus can directly measure the raw exhaust gas or thetreated exhaust gas without conditioning. An optical device 3 in frontof the segment access, e.g., a lens or a combination of several lenses,one or more apertures, etc., can have a favorable influence on the beamcourse for the test area, e.g., by expanding or focusing it. The beamcourse 2 can also be favorably composed with the use of optical fibers,completely between the laser 1 and the optical access 4 or also only inpartial areas thereof.

With the backscattering arrangement in FIG. 1, the recording beam course6, which can likewise be partially or completely composed of opticalfibers, leaves the test area 5 on the same side e.g., inside the circleor pipe segment, on which the input beam also takes place. This can takeplace via the same optical access or via one of this type in theimmediate vicinity. The measurement signal is also conveyed to adetector unit 8 in the beam course 6 parallel to the input beam, ifnecessary even using the same beam course 2, or also independent of it.When using the same beam course 2 and 6 another optical element 10 isplaced in the beam course, which element spatially divides the signalbeam course from the input beam and deflects it in the direction of thedetector unit 8. An optical unit 7 is located in front of the detector8, which unit differs according to the process, and which, e.g., can becomposed of apertures, lenses and in particular also different filters(gray filters, interference filters and/or cut-off filters) or also incombination with spectrographs or monochromators, with the aid of whichthe measuring signal is processed according to the desired signalinformation in terms of intensity and/or spectrally. The detector unit8, e.g., one or more photomultipliers, one or more photodiodes, one ormore CCD or streak cameras, or also combinations of several suchoptoelectronic components, processes the optical signal into an electricdatum that can be further processed in an electronic processing system9, e.g., a computer, a correlator, etc., and processed for use, e.g., inmeasuring circuits and closed loops in, e.g., test bed peripheralequipment, as a control system also, e.g., in combination with on-boarddiagnostics (OBD) in the vehicle itself.

FIG. 1 shows by way of example three different measuring processesaccording to the device connected in an arrangement, whereby accordingto the invention the above-mentioned LIBS, LAF and LRS techniques can becombined with the LII technique or also LAT instead of LIBS, LAF or LRS,provided that the output of a multi-pass device used is located on theinput beam side (in general at least one irradiation direction accordingto FIG. 3 is required for LAT). With a suitable choice of the input beamlight source 1, all measuring processes can be operated from only onelight source or alternatively also with different input beam lightsources (1A and 1B additionally) specially optimized for the respectiveprocess. The same applies to the input beam courses 2, 2A, 2B andrecording beam courses 6, 6A, 6B, the detector units 8, 8A, 8B used andthe optical elements 7, 7A, 7B placed in front thereof. If all threeprocesses are provided with specific beam courses and the same beamcourses can be used for input beam and signal detection, separating andif necessary also deflecting optical elements 10, 10A, 10B should beincluded in each one of them. Such elements are also used to separatedifferent signal beams if they use the same beam course from the testobject.

Alternatively to FIG. 1, FIG. 2 shows a device according to theinvention in which by way of example input beam and recording beam hereagain form a 90 degree arrangement for three different techniques. Thedescription of FIG. 1, with all statements and conclusions, is alsoapplicable to FIG. 2 in its entirety, except that here fordevice-related reasons elements 10A and 10B no longer separate inputbeam and signal beam from one another, but here only different signalbeam courses according to the different measuring processes.

The same applies to FIG. 3, where a device according to the invention isshown in diagrammatic form, in which the signal beam course isconstructed behind the test volume, thus opposite the input beam side(thus as a 180-degree or transmission arrangement). Such an arrangementprovides the simplest method for combinative inclusion of the LATprocess.

In addition to the devices shown in diagrammatic form in FIGS. 1-3,according to the invention all possible combination forms can also beembodied separately regarding the position of input beam and recordingbeam course relative to the test area and relative to one another forall referenced measuring processes, whereby angled arrangements, otherthan 0, 90 and 180 degrees, can be selected for individual and/or allreferenced measuring processes.

FIG. 4 shows in diagrammatic form a possible application of theinvention in the testing and characterization of an engine exhaust gasin raw state behind the exhaust gas manifold of an engine M and in frontof, e.g., a first catalytic converter 20, e.g., an oxidation catalyticconverter, at the measuring point 50, of the treated exhaust gas behindthe catalytic converter 20 at the measuring point 60 and at themeasuring point 70 in front of, e.g., a particle filter 30—measuringpoints 60 and 70 could also represent only one measuring point accordingto the invention—and behind this at measuring point 80 which again canbe placed simultaneously or separately in several measuring points,e.g., in front of a second catalytic converter 40, e.g., a NO_(X)storage catalytic converter. Another measuring point 90, for example, isthen located behind this catalytic converter 40, from which measuringpoint—as from all the other measuring points as well—the measuredinformation is passed to the test bed peripheral equipment or thecentral unit of an OBD system 100 which then, e.g., in the latter casealso can have an active influence on the engine operation or theindividual components of the exhaust gas after treatment. Theseprinciples are also applicable to any other exhaust gas system,regardless of its respective composition and differently for sparkignition engine and diesel engine applications. In this case, a devicewith LII, LIBS, LRS and LAT (in particular ë) could be installed e.g. atmeasuring point 50, that with LAT and/or LRS and LII or also LIBS at themeasuring points 60 and 70, possibly alternatively to 50, LAT (inparticular ë), LII and LIBS (and/or LRS) at measuring point 80 and LAT(i.a., also in particular NH3) and LRS at measuring point 90. Many othergroupings and combinations are useful and provided according to theinvention. Some of the measuring points are equipped in connection witha sensor to record the exhaust gas temperature, which is alreadycontained in the LII sensor according to the invention (German patentapplication DE 19904691 A1).

1. A device for practicing a process for determining properties ofliquid particles of engine exhaust gas, wherein the process comprisesdetecting Raman scattering produced in a test area by excitation withone of a laser, a laser diode, and a diode laser, and determining atleast one of a type and composition of individual constituents of theliquid particles of the engine exhaust gas and concentrations ofindividual constituents of the liquid particles of the engine exhaustgas, the device comprising a test volume located inside an exhaust gaspipe and at least one of: a detector unit comprising one of opticalfibers and parts of optical fibers and being structured and arranged tocharacterize the engine exhaust gas; a detector unit and a plurality ofoptical components and being structured and arranged to characterize theengine exhaust gas; and a device enclosing the engine exhaust gas and adevice for one of avoiding contamination and reducing contamination. 2.The device of claim 1, wherein the device comprises the detector unitcomprising one of optical fibers and parts of optical fibers.
 3. Thedevice of claim 1, wherein the device comprises the detector unit andthe plurality of optical components.
 4. The device of claim 1, whereinthe device comprises the device enclosing the engine exhaust gas and thedevice for one of avoiding contamination and reducing contamination. 5.A device for practicing a process for determining properties of solidparticles of engine exhaust gas, wherein the process comprises detectingradiation produced in a test area by laser-induced breakdownspectroscopy (LIBS) after irradiation with one of a laser, a laserdiode, and a diode laser and determining a type and composition of thesolid particles of the engine exhaust gas, the device comprising a testvolume located inside an exhaust gas pipe and at least one of: adetector unit and a plurality of optical components structured andarranged to characterize the engine exhaust gas; a detector unitcomprising one of optical fibers and parts of optical fibers and beingstructured and arranged to characterize the engine exhaust gas; and adevice enclosing the engine exhaust gas and a device for one of avoidingcontamination and reducing contamination.
 6. The device of claim 5,wherein the device comprises the detector unit and the plurality ofoptical components.
 7. The device of claim 5, wherein the devicecomprises the detector unit comprising one of optical fibers and partsof optical fibers.
 8. The device of claim 5, wherein the devicecomprises the device enclosing the engine exhaust gas and the device forone of avoiding contamination and reducing contamination.
 9. A devicefor practicing a process for determining properties of liquid particlesof engine exhaust gas, wherein the process comprises detecting radiationproduced in a test area by laser-induced breakdown spectroscopy (LIBS)after irradiation with one of a laser, a laser diode, and a diode laserand determining a type and composition of the liquid particles of theengine exhaust gas, the device comprising a test volume located insidean exhaust gas pipe and at least one of: a detector unit and a pluralityof optical components structured and arranged to characterize the engineexhaust gas; a detector unit comprising one of optical fibers and partsof optical fibers and being structured and arranged to characterize theengine exhaust gas; and a device enclosing the engine exhaust gas and adevice for one of avoiding contamination and reducing contamination. 10.The device of claim 9, wherein the device comprises the detector unitand the plurality of optical components.
 11. The device of claim 9,wherein the device comprises the detector unit comprising one of opticalfibers and parts of optical fibers.
 12. The device of claim 9, whereinthe device comprises the device enclosing the engine exhaust gas and thedevice for one of avoiding contamination and reducing contamination. 13.A device for practicing a process for determining concentrations ofgaseous constituents of engine exhaust gas, wherein the processcomprises detecting radiation produced in a test area by laser-inducedbreakdown spectroscopy (LIBS) after irradiation with one of a laser, alaser diode, and a diode laser and determining a type and concentrationof individual gaseous constituents of the engine exhaust gas, the devicecomprising a test volume located inside a pipe or channel segment and atleast one of: a detector unit and a plurality of optical componentsstructured and arranged to characterize the engine exhaust gas; adetector unit comprising one of optical fibers and parts of opticalfibers and being structured and arranged to characterize the engineexhaust gas; and a device enclosing the engine exhaust gas and a devicefor one of avoiding contamination and reducing contamination.
 14. Thedevice of claim 13, wherein the device comprises the detector unit andthe plurality of optical components.
 15. The device of claim 13, whereinthe device comprises the detector unit comprising one of optical fibersand parts of optical fibers.
 16. The device of claim 13, wherein thedevice comprises the device enclosing the engine exhaust gas and thedevice for one of avoiding contamination and reducing contamination. 17.A system for determining concentrations of gaseous constituents ofengine exhaust gas, the system comprising: a test area comprising anoptical access; a light source emitting an optical beam towards theoptical access; the light source comprising one of a laser, a laserdiode, and a diode laser; an optical device disposed between the opticalaccess and the light source; at least one detector unit receiving anoptical beam passing through the optical device from the optical access;and an electronic processing system communicating with the at least onedetector unit.
 18. A system for determining concentrations of gaseousconstituents of engine exhaust gas, the system comprising: a test areacomprising a first optical access and a second optical access; a lightsource emitting an optical beam towards the first optical access; thelight source comprising one of a laser, a laser diode, and a diodelaser; an optical device disposed between the first optical access andthe light source; at least one detector unit receiving an optical beamfrom the second optical access; and an electronic processing systemcommunicating with the at least one detector unit, wherein the systemdirectly measures raw exhaust gas via a test volume located inside anexhaust gas pipe.